Hardened-steel plate and like article.



' UNITED STATES HARDENED-STEEL PLATE AND LIKE ARTICLE.

No Drawing.

Specification of Letters Patent. Application filed June 8, 1910. Serial No. 564,781.

Patented Aug. 20, 19i2.

on one surface are required. In known processes for the manufacture of such plates,

a mild steel containing 0.3 per cent. of carbon is subjected to a cementation process, the plates being placed in a furnace and covered with carbon on one side, and then heated for seven or eight days at a red heat. The plates are then quenched in water, which hardens the portion of the steel which has been carburized. In some cases the steel before hardening has been heated to a red' heat and plunged m water, and then again heated to a somewhat lower heat, and again plunged in water to give the plate a fibrous structure, the fibrous plate being then bardened by subjecting the surface which requires hardening to a highertemperature,

and quenchlng.

The object of the present invention is to obtain a cement steel plate or like article.

having a glass hard surface which will be especially adapted for armor plates and similar purposes, and the invention includes a plate of the novel composition hereinafter described and particularly defined by the appended claims.

In producing a plate according to my invention, I prepare an alloy containing molybdenum or tungsten or the equivalent quantity of both, and from .2 to .5 per cent. of carbon, subjecting the same to a cementetion process, whereby a glass hard surface is produced without quenching, the molybdenum being distributed throughout the plate or article, and the carbon through the back portion of the plate or article in the proportions specified with a further proportion of carbon in the face of the plate or article, the process being carried out by any open hearth process by Wh'ch a pure steel free from phosphorus and sulfur can be obtained.

I find that improved results may be secured by using nickel in connection with the foregoing ingredients, and improved armor plates may advantageously be secured by providing ingots containing one per cent. of molybdenum, four per cent. of nickel, and three tenths per cent. of carbon, which ingots are rolled to the desired thickness of plate, and the plates covered with oak charv coal or other carbon on one surface, and heated for from seven to eight days at a red heat, as is usual in the cementation process. Other articles can be formed and their surfaces treated in a similar manner.

By the above treatment a plate having a glass hard surface is obtained without quenching.

I also find that all or part of the nickel may be replaced by cobalt.

Having now described my invent-ion what I claim as new and desire to ters Patent is 1. Cement steel plates or other articles having a glass-hard surface containing molybdenum at least 1 per cent. throughout the plate or article, cent. through the back portion of the plate or article and a further proportion of carlpon the face of the plate or article, as set ort secure by Let- 1 carbon 0.2 to 0. 5 per 2. Cement steel plates or other articles HAROLD ASHTON RICHARDSON.

Witnesses: V

-ANNIE F. KAHN,

P. A. OUTHWAITE. 

